Supplemental Cash Flow Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Other Significant Noncash Transactions [Line Items]
Payments to acquire businesses	$ 8,100	$ 500	$ 9,785	$ 1,858
Supplemental cash flow information
Interest paid			109,332	109,699
Income taxes paid			9,878	8,900
Changes in accounts payable related to purchases of revenue earning equipment			3,902	1,670
Operating and revenue earning equipment acquired under capital leases			3,788	5,500
Other Acquisitions Completed in Prior Years [Member]
Other Significant Noncash Transactions [Line Items]
Payments to acquire businesses			$ 1,649	$ 1,858